1. Field of the Invention
The present invention relates to a key apparatus for a vehicle, a method of controlling the starting of a vehicle engine, and a key system for a vehicle, and more particularly to a key apparatus for a vehicle, a method of controlling the starting of a vehicle engine, and a key system for a vehicle, which transmit a first signal when instructed by instructing means for instructing transmission of the first signal, and which transmit a second signal when receiving electric power from an electric power transmitting means provided at a vehicle.
2. Description of the Related Art
Conventionally, there has been suggested a keyless entry system comprising an ignition key and a door locking and unlocking apparatus. The ignition key transmits a key code stored in advance in a memory when an operating switch provided in a body surface of a grip is operated. The door locking and unlocking apparatus receives a key code transmitted from the ignition key. In a case in which the received key code coincides with the key code stored in advance, the apparatus judges that the key code is transmitted from an appropriate ignition key, and locks and unlocks the door.
Further, there has been suggested an immobilizer (a transponder) which is structured so as to electromagnetically connect an antenna coil in the ignition key and an antenna coil in a vehicle (the key cylinder) to each other in the case in which it is detected that the ignition key is inserted into the key cylinder. By supplying electric power to the ignition key, a key code is transmitted from the ignition key, and the key code is received by the vehicle. When the key code is received by the vehicle and the received key code coincides with a key code stored in advance, it is judged that the key code has been transmitted from an appropriate ignition key, and starting of the engine is permitted.
Since operation becomes complex when the keyless entry system function and the immobilizer function are independently provided in the ignition key, there has been suggested a key unit commonly having these respective functions (Japanese Patent Application Laid-Open (JP-A) No. 7-324533).
However, in the case in which this transponder for the immobilizer is incorporated within the ignition key for the keyless entry system, when the key blade is inserted into the key cylinder or the ignition key is rotated, there is the concern that a switch disposed on the body surface of the grip may be erroneously operated and the key code for the keyless entry system may be transmitted by radio waves such that communication of the transponder is prevented.